Transmission Characteristics Of Side-coupled Waveguide-cavity Systems

Optical microcavity structure is an important platform to study the interaction between light and matter,and it also plays an important role in the research of the application of optical equipment.Professor Fan Shanhui of Stanford University studied the transmission characteristics of the optical microcavity and waveguide side coupling system and discussed its application in sensing.Professor Fan's article has attracted a lot of attention.This thesis makes a more general extension of Professor Fan's research results.The thesis first introduces some basic background knowledge of optical microcavities,including the classification of optical microcavities and the physical parameters describing the properties of optical microcavities.The thesis then introduces the optical transmission matrix method,including the relationship between the transmission matrix and the scattering matrix,and the transmission matrix of some optical devices.Finally,the transmission matrix method is used to simulate the waveguide and optical microcavity side coupling system.The optical transmission characteristics of the coupling system in the case of embedding two partially reflecting elements and one partially reflecting element in the waveguide are studied respectively.When two partially reflecting elements are embedded in the waveguide,sharp symmetrical lines and asymmetric lines can be observed in the transmission line.The results show that the position of the microcavity relative to the two partially reflecting elements has an important influence on the transmission.When the microcavity is not in the middle of the two partially reflecting elements,a narrower transmission line shape can be obtained.When only one partially reflecting element is embedded in the waveguide,a sharp asymmetrical line shape can be observed in the transmission line of such an optical system.The results show that when the cavity resonance frequency of the microcavity takes a specific value,the change of the system transmission near the resonance frequency of the microcavity is very steep,and it can quickly change from completely opaque to fully transparent.When the angular frequency of the incident light is not nearthe microcavity resonance angular frequency,the transmission line is relatively flat.The research results of the thesis can be applied to the study of optical switches.